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Shubin Zhang,Tianxiao Wang,Xin Guo,Shengwen Chen,Lijun Wang 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.4
Sulfidated and bimetal modification can improve the reactivity and selectivity of zero-valent iron in contaminant removal. However, previous studies were focused on unilateral material approaches. In this article, a new hybrid composite Ag/S-ZVI was prepared by doping elemental silver on surface of sulfidated nanoscale zerovalent iron (S-nZVI). The results of X-Ray Diffraction (XRD), energy dispersive spectrometer (EDS) and X-ray Photoelectron Spectroscopy (XPS) indicated Ag was dispersed on the surface of S-nZVI. Scanning electron microscope (SEM) images displayed Ag/S-ZVI was irregular clusters with rough surfaces, small agglomeration, and quasi-spherical in shape. The removal of TCE by Ag/S-ZVI was 90.4% within 20 min. The reaction rate constant Kobs of Ag/S-ZVI was 2.59 times or 1.85 times of nZVI or S-nZVI, respectively. Cycling experiments showed that Ag/S-ZVI had good recycling ability, and the removal rate of TCE reached 72.6% at the third cycle. The addition of Ag+ makes S-nZVI as an abundant and efficient source of reducing electrons. The Fe<SUP>0</SUP> core can break C-Cl bonds by releasing electrons and the surface layer of Ag favors the transfer efficiency of electrons. Such study provides an efficient and robust ternary system for the remediation of TCE in groundwater.
Sensitivity analysis of rolling bearing fatigue life under cyclic loading
Xianming Wang,Qingling Meng,Tianxiao Zhang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11
Rolling bearings are regularly subjected to cyclic loading, and the load changing sequence has a significant influence on bearing fatigue life. The study offers a cumulative fatigue damage theory based on the improved Lundberg-Palmgren method that takes into account the effect of load changing sequence on bearing fatigue life and then proposes a modified Miner bearing fatigue life model. Additionally, the state function for the bearing fatigue life analysis is developed based on the basic dynamic load rating and stress-strength interference model of the bearing. A moment-based sensitivity analysis method for bearing fatigue life is proposed for studying the influence of different variables on bearing fatigue life. Finally, a sensitivity analysis of the fatigue life of 6209 deep groove ball bearings was performed as an example. The calculation results demonstrate that the modified Miner life model is comprehensive and that the moment-based sensitivity analysis method is simple and accurate.